As part of an ongoing program of study of the physicochemical properties of interacting macromolecules in solution, it is proposed to continue and extend our investigations into: (a) the interaction of chlorpromazine (Thorazine) with tubulin in order to gain insight into the molecular mechanism of action of this drug; (b) the secondary structure of bradykinin and its analogs as probed by the method of CD; and (c) the theory of molecular-sieve chromatography of interacting macro-molecules. In addition, it is proposed to initiate a CD study on the luteinizing hormone releasing hormone. The chlorpromazine-tubulin interaction will be studied by the combined application of molecular-sieve chromatography, ultracentrifugation and ORD-CD.